The potent effects of brain peptides and the possibility of using these compounds for therapeutic purposes makes their metabolism of great current interest. Information regarding oligopeptide degradation however, is scattered and incomplete, and how brain peptidases act together to effect the breakdown of a complex substrate is not known. We therefore propose to investigate, in detail, the degradation of adrenocorticotropic hormone both as a model substrate to elucidate mechanisms of peptide metabolism in brain, and to obtain information about the formation and stability of specific ACTH sequences known to have behavioral activity. Preliminary results indicate that new peptidases will be found and that useful data concerning the properties of known hydrolases will be obtained. We will begin by studying a group of small overlapping sequences. This information will then be applied to successively larger hormonal fragments. For each peptide, the mechanism of degradation will be determined from the time-course of amino acid release and from information about peptide fragments obtained by dansylation and HPLC techniques. Peptidases cleaving specific bonds will be isolated and their action on ACTH fragments confirmed. Initially we will use mouse brain cytosol as a enzyme source. However, as the mechanisms of degradation of individual ACTH fragments become known, these will be compared to breakdown produced by synaptosomes, membrane preparations, and lysosomes. Areas of the brain which are known to contain ACTH will be compared to regions where the hormone is absent. Generalizations as to oligopeptide metabolism will be extended using other peptides of neurochemical interest.